Six major banking and real estate industry organizations are preparing a concerted effort aimed at persuading Congress and the Bush administration to restore some of the real estate tax breaks that were repealed in 1986.

The level of cooperation stops short of a formal alliance, but "I think you're going to see six major trade groups walking in lockstep" on the issue, Frederick L. Webber, president of the U.S. League of Savings Institutions, said yesterday at the organization's annual meeting in San Francisco.

Besides the U.S. League, the other groups involved are the National Council of Savings Institutions, the American Bankers Association, the National Association of Home Builders, the National Association of Realtors and the Mortgage Bankers Association of America.

The six met last week to discuss the issue and plan to meet again in about two weeks, according to officials of several of the organizations.

Many members of the groups are suffering from sagging real estate values across the country and view the Tax Reform Act of 1986 as a major factor in that decline. The law wiped out a wide array of tax benefits that were viewed by many to be so generous that they spawned massive overbuilding and a highly profitable industry devoted entirely to tax shelters.

Many advocates of the 1986 law argued that the benefits helped draw capital out of more productive sectors of the economy and stimulated the excesses that led to the current economic downturn. Norman D. Flynn, president of the National Association of Realtors, said, "My sense is we will be singing out of the same songbook on these issues. Whether or not we walk in lockstep remains to be seen," in reply to Webber's characterization of the effort.

Industry spokesmen do not necessarily disagree that the earlier tax benefits were especially generous, but they argue that the change was too abrupt, giving investors and lenders no chance to adjust.

"The door was swung wide open in 1981" when many of these benefits were enacted, "and a lot of people found it attractive to be in real estate. Then in 1986 the door was slammed shut," leaving investors and lenders out on a limb, said James E. O'Connor, tax counsel of the National Council of Savings Institutions.

The real estate slump has not only led to the collapse of many thrift institutions, it is depressing the value of the properties taken over by the government in the savings and loan cleanup. It is clear several of the groups will argue that a return of at least some of the tax breaks would boost values, cutting the cost of the S&L cleanup and perhaps saving some marginal institutions from collapse.

Before 1986, owners of property were entitled to write off losses against income from any source. They received accelerated depreciation -- rapid write-offs of paper losses attributable to wear and tear -- and when property was sold it qualified for a lower capital gains tax rate.

In addition, deductions could be worth 50 cents on the dollar to a taxpayer in the top bracket.

The 1986 law lowered the top rate, cutting the value of deductions. It eliminated the capital gains preference, reduced depreciation write-offs and sharply restricted the ability of taxpayers to use real estate losses to shelter other kinds of income. It is this area, known as "passive losses," that is attracting the most attention.

"We are not advocating reinstituting the tax shelter business," O'Connor said. But part of the law that subjects all rental real estate to the passive loss rules "is unfair" and is "one of the things that have caused the real estate collapse," he said.

O'Connor said his group figures this change would cost the Treasury about $3 billion, but "there should be an offset" from the savings the government will realize from improvements in the S&L industry.

The idea, said Kent Colton of the National Association of Home Builders, was to get "real estate entrepreneurs treated {the same} as entrepreneurs in any other business."

He said "there was a lot of interest, especially on House side" in the last Congress, and added that he believes "we will be able to continue to generate that kind of interest next year."

Colton cautioned, though, that the groups recognize the severity of the budget deficit problem and that "it's a long, hard discussion. It's not going to happen in February 1991."

Knight contributed to this report from San Francisco and Crenshaw from Washington.